Re: [PATCH] ALSA: hda: runtime PM is always active

[Sameer Pujar]

On 1/24/2019 9:34 PM, Takashi Iwai wrote:
> On Thu, 24 Jan 2019 16:57:11 +0100,
> Sameer Pujar wrote:
> > The runtime PM count is incremented and set to active during hda codec
> > device init, but it is decremented and set to suspend during exit only.
> > Hence the runtime PM status is always active and hda device cannot be
> > put to runtime suspend. Keeping device usage active for entire period,
> > though nothing really happening on the device, seems unnecessary.
> >
> > This patch avoides incrementing runtime PM usage count of the device.
> >
> > Signed-off-by: Sameer Pujar <spujar@xxxxxxxxxx>
> > Reviewed-by: Ravindra Lokhande <rlokhande@xxxxxxxxxx>
> > Reviewed-by: Mohan Kumar D <mkumard@xxxxxxxxxx>
> This breaks the existing things, I'm afraid.
> Did you really test and verify the behavior...?
>
> The runtime PM refcount is decremented at snd_hda_codec_register(),
> and that's the place to let runtime suspend of the codec really
> effective.  (It's not about the controller, though.)
It worked fine at my end. I could put the device to runtime suspend and 
resume it back multiple times.
Since you are suggesting it could break things, let me rework on the 
patch and dig up a little more to
see if there is better way to fix this.

Thanks,
Sameer.

> thanks,
>
> Takashi
>
>
> > ---
> >   sound/hda/hdac_device.c | 6 ------
> >   1 file changed, 6 deletions(-)
> >
> > diff --git a/sound/hda/hdac_device.c b/sound/hda/hdac_device.c
> > index 95b073e..72aa342 100644
> > --- a/sound/hda/hdac_device.c
> > +++ b/sound/hda/hdac_device.c
> > @@ -31,9 +31,6 @@ static void default_release(struct device *dev)
> >    *
> >    * Returns zero for success or a negative error code.
> >    *
> > - * This function increments the runtime PM counter and marks it active.
> > - * The caller needs to turn it off appropriately later.
> > - *
> >    * The caller needs to set the device's release op properly by itself.
> >    */
> >   int snd_hdac_device_init(struct hdac_device *codec, struct hdac_bus *bus,
> > @@ -55,8 +52,6 @@ int snd_hdac_device_init(struct hdac_device *codec, struct hdac_bus *bus,
> >   	codec->bus = bus;
> >   	codec->addr = addr;
> >   	codec->type = HDA_DEV_CORE;
> > -	pm_runtime_set_active(&codec->dev);
> > -	pm_runtime_get_noresume(&codec->dev);
> >   	atomic_set(&codec->in_pm, 0);
> >   
> >   	err = snd_hdac_bus_add_device(bus, codec);
> > @@ -123,7 +118,6 @@ EXPORT_SYMBOL_GPL(snd_hdac_device_init);
> >    */
> >   void snd_hdac_device_exit(struct hdac_device *codec)
> >   {
> > -	pm_runtime_put_noidle(&codec->dev);
> >   	snd_hdac_bus_remove_device(codec->bus, codec);
> >   	kfree(codec->vendor_name);
> >   	kfree(codec->chip_name);
> > --
> > 2.7.4